Pedal switch foe electric motors



(No Model.) 3 Sheets-Shaet 1.

L. TEAL. PEDAL SWITCH FOR ELECTRIC MOTORS.

No.- 497,144. Patented May 9,1893.

WITNESSES: INVENTOR:

as on. woTnLlmpuyvsumoTov n c (No Model.) 3 Sheets--Sheet 2.

L. TEAL. PEDAL SWITCH FOR ELECTRIC MOTORS. No. 497,144. Patented May 9,1893.

WITNESSES: 5 INVE'NTOR: @MWW9-. zmzzl (No Model.) 3 Sheets-Sheet 3.

L. TEAL.

PEDAL SWITCH FOR ELECTRIC MOTORS. No. 497,144. Patented May 9, 1893.

UNITED STATES PATENT OFFICE LEVI TEAL, OF PHILADELPHIA, PENNSYLVANIA,ASSIGNOR TO THE S. S. WHITE DENTAL MANUFACTURING COMPANY, OF SAME PLACE.

PEDAL-SWlTCH FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 497,144, dated May 9,1893.

Application filed January 16, 1893. Serial No. 458.563. (No model.)

To all whom it may concern:

Be it known that I, LEVI TEAL, of the city and county of Philadelphiaand State of Pennsylvania, have invented certain new and usefulImprovements in Pedal-Switches for Controlling Electric Motors, of whichthe following is a specification.

My invention relates to certain improvements, hereinafter specificallyclaimed, in foot-actuated switch controlling mechanism for electricmotors applicable to use for operating dental engines. My object is toprovide in compact form simply constructed mechanism by the actuation ofwhich to stop, start, and reverse the direction of rotation of theelectric motor.

In the accompanyingdrawingsFigure 1 represents in perspective asnitableembodiment of my invention. Fig. 2 is a vertical central section withparts shown in elevation. Fig. 3 is a bottom view or inverted plan withthe bottom plate of the switch box or case removed. Fig. at is a view onan enlarged scale of the reversing contacts detached as seen from theunder side. Fig. 5 is a diagram designed to illustrate the circuitsthrough the motor, its armature, the pedal switch mechanism and theelectro-magnetic clutch mechanism. Fig. 6 is a side elevation of themotor with the sufficiently indicated clutch mechanism and a cableconnecting plate in proper position.

Conductors A A for the electric current connect respectively withbinding posts a a 011 an insulated connecting plate C secured to theframe. of a suitable motor A Binding post a is electrically connected byconductor B with one terminal of the ordinary field coil of the motor.The other terminal binding post I) of the field coil is electricallyconnected by conductor B with the inner end of a binding post 17 of theconnecting plate C. This plate serves as a medium for electricallyconnecting the motor by the cable D with switch mechanism in particularway as to be explained. The cable is shown as composed of five insulatedconductors, one of which,D, is connected at one end to the binding post5 and at its opposite end to a contact plate cl mounted on a reversinglever D composed of suitable non-conducting material. This lever isjointed to have sidewise horizontal movement by means of a pivot C whichconnects it with the base of a suitable foot pedal G. This pedal base isof nonconducting material in the form of a shallow box or case G havinga detachable bottom -g. The switch box is provided with a foot guard orstirrup G2 upon which is secured a tubular spring standard 9. The cableof conductors passes through this standard and the conductors aredivided and pass in two groups by the opposite sides of the stirrup totheir respective contacts in the switch box.

The reversing leverD carries asecond contact plate II which iselectrically connected by conductor H to a contact plate H extendingthrough and slightly above the switch box beneath one end of the pedalG. Near the contact plate H the conductor H is coiled to give itflexibility so as not to interfere with the movements of the reversinglever. A contact plate E having two forks terminating respectivelyinspriugs e and e, is so placed adjacent to the free end of thereversing lever D that by movement of this lever in one direction thecontact plate cl may be engaged with the fork e of the contact plate E,while movement of the lever in the other direction serves to engagecontact II with the fork e of this contact plate. A contact plate Fterminates in a spring arm or end f projecting between the forks of thecontact plate E. By reference to Fig. 4: it will be seen that whencontact cl engages contact fork c, the contact II necessarily engagesend f of contact F, and that with contact II in engagement with contactfork 6, contact d necessarily engages contact end f.

To adapt the reversing lever to be actuated by the foot it is connectedby a pin t' with an endwise sliding rod I which passes transverselythrough the switch box and is provided at its ends with controlling armsI I. The connecting pin 2' projects at its lower end into a hole in thereversing lever,- is rigidly connected at its upper end with the sliderod I, and travels in a slot 1" of the switch box when the slide rod isactuated.

Electrically connected with the forked contact plate E is a conductor Eof the cable, which is also electrically connected with binding post eof the cable connecting plate 0, and with the brush J resting on thecommutatorJ of the motor armature. Contact plate F is electricallyconnected by conductor E of the cable with binding post a of thecableconnecting plate and with the other brush J of the commutator T.

The binding post a of the connecting plate is electrically connected bya conductor K with a spring contact plate K which is rigidly securedmidway its length to the top of the switch box beneath the pedal. Theconductor K is shown as secured to the under side of this spring contactplate at its center. The ends of this spring contact plate bear upwardagainst the under side of the pedal near the opposite ends thereof, andwhen the action of this plate is not interfered with by actuating thepedal it holds the pedal in its level or normal position in which it isrepresented in Fig. 2. Upward movement of the ends of this springcontact plate is limited by screws 7c, and in this way an equal upwardpressure upon both ends of the pedal by the spring contact plate isprovided for. The binding post 6 of the connecting plate is alsoelectrically connected by a conductor L with suitable electro magneticclutch mechanism indicated at M, for throwing a pulley on the armatureshaft of the motor into and out of engagement with said shaft. From theclutch mechanism a conductor N electrically connects with a binding postit of the connecting plate and with a contact plate 0 under one end ofthe pedal and passing through the top of the switch box.

In operation, to start the motor the spring contact plate K is broughtinto contact with the contact plate 11, by depressing the heel end ofthe pedal, thus completing the electric circuit through the motor asfollows:-The current from the main line binding post a passes throughconductor B to binding post I), through the field of the motor to thebinding post I), thence by conductor 13, the binding post b andconductor D of the cable, to the contact plate (1 of the reversingleverD and when this lever is in position asshown in Fig. 2 the current nextpasses to contact plate E and through conductor E, to binding post 6 ofthe connecting plate and to the brush J; thence through the commutatorand armature of the motor, and the brush J and through conductor E byway of binding post 6 of connecting plate to contact plate F, throughcontact piece H and conductor H to contact plate H; thence throughcontact spring K and conductor K to binding post a and out at main line.To reverse the direction of: rotation of the motor, the electricalconnections just described are maintained with the following exceptions:The reversing lever is actuated by pressure of the side of the foot ofthe operator upon the proper arm I to move the slide rod 1 in thedirection to cause engagement of contact plates (1 and II respectivelywith contact plate F and the fork c of contact plate E. The current nowpasses through the field of the motor as before described, until theplate d is reached, and next through contact plate F, conductor Ebinding post a brush J the commutator, the motor armature, the brush J,the conductor E by way of binding post 6 to contact plate E, thence bycontact plate H and so on to main line as before explained. Then thepedal is allowed to assume a horizontal position as shown by Fig. 2, theelectric circuit is broken between K and II, and the motor graduallycomes to rest. To suddenly stop the driving pulley which connects insuitable way with the external work to be done, the toe end of the pedalis depressed to cause contact-spring K to engage contact plate 0, and anelectric circuit is now made as follows:-From main line, through bindingpost a, conductor 13, binding post I), field of motor, binding post I),conductor B, binding post conductor L, magnetic clutch mechanism M,conductor N, by way of binding post a, to contact plate 0 and throughspring contact K, and conductor K to main line by binding post a.

I claim as my invention-- 1. The combination, in an electric motorcontroller, of the pedal, the pedal base, the reversing lever pivoted atone end in the pedal base, the two contact plates carried by thereversing lever, the contact plate having two forks, the contactplatehavingthearm projecting between said forks, the slide rod connectedwith the reversing lever, and the controlling arms of the slide rod,substantially as set forth.

2. The combination, in an electric motor controller, of the pedal, thepedal base, the spring contact plate beneath the pedal and bearingupwardly against it, the contact plate with which said spring contactplate is engaged by depression of the pedal heel, the reversing leverpivoted at one end in the pedal base, the two contact plates carried bythe reversing lever, the contact plate having two forks, the contactplate having the arm projecting between said forks, the slide rodconnected with the reversing lever, and the controlling arms of theslide rod, substantially as set forth.

In testimony whereof I have hereunto subscribed my name.

LEVI TEAL.

Witnesses:

R0111. E. GORDON, H. H. MUsrIN.

